This invention relates to a safety device for use with machines wherein there is danger of injury to the operator if the operator accidentally places his hands in an improper position during the operation of the machine. This invention is particularly applicable to such machine tools as punch presses, where accidental dropping of the ram can cause serious injury. However this invention is not limited in its application to punch presses, but is generally applicable to any machine where the hands of the operator should be in a safe position during operation of the machine.
Safety devices have been described in the past which require both hands for starting a machine and thus keep the hands out of the reach of the machine, as for example U.S. Pat. Nos. 786,473; 1,046,373; 1,170,615; 1,556,054; 2,541,577; 2,545,549; 2,559,495; 2,594,520; 2,669,686; 3,103,270 and 3,791,496. These prior art devices have one or more disadvantages, as for example, complexity, high cost, lack of reliability and difficulty in installation.
One object of the present invention is to provide a simple, reliable safety device which can be readily attached to a machine with a minimum of expense.
Further objects and advantages of the present invention will be apparent from the description and claims which follow taken together with the appended drawings.